[Ed. note: The following description of BZ effects is reproduced verbatim from Ketchum JS. Chemical Warfare; Secrets Almost Forgotten. James S. Ketchum, MD. 2006. pp. 46-50. It is composed of excerpts from a report that summarized data from a series of experiments conducted with volunteers at the Edgewood Arsenal. See "Citation" above.]

Following the administration of an incapacitating dose of BZ [7 ug/kg, ed.], a typical sequence of events occurs. The onset is more or less insidious, with the first symptoms becoming noticeable at about one hour. Early central nervous system manifestations include heightened deep tendon reflexes, ataxia, incoordination, slurring of speech, dizziness and headache. Nausea, usually without vomiting, is frequent. Subjective weakness, without appreciable loss of strength, occurs primarily in the legs.

During the first phase (1-4 hours), discomfort and apprehension are present. Extreme restlessness occurs, sometimes with involuntary clonic spasms of the extremities and birdlike flapping of the arms. Errors of speech and scattered moments of confusion may be noted.

After a crescendo of restlessness and ataxia, a second phase (at 4-12 hours) begins.

During the second phase, sedation, stupor, and even semi-coma develop. The individual sleeps, or appears to sleep, and responds only to direct and sometimes only to strong, stimulation. Spontaneous groping or crawling may alternate with lying quietly. The subject mutters incoherently from time to time. Sometimes he shows "obstinate progression" as he stubbornly tries to crawl in a straight line over, past and through all obstacles. As this primitive behavior (reminiscent of the "running response" in decorticate animals) subsides, the subject enters a third phase, beginning at during 12 hours, during which more spectacular symptoms develop.

"Hallucinations seem to dominate the field of awareness, and real objects and persons are generally ignored or ludicrously misrepresented. Touch seems to become the most important sensory system, and the hands are ceaselessly active, exploring clothing, bedding, walls, floors and crevices of the environment. Smoking and drinking of phantom cigarettes and beverages are very common. "

As speech returns over the next few hours, it is in clipped, flat accents, containing rapid bursts of commonly associated words and phrases, particularly those that are most colloquial and habitual. Logical continuity is lacking and most sentences are meaningless or absurd. Hallucinations seem to dominate the field of awareness, and real objects and persons are generally ignored or ludicrously misrepresented. Touch seems to become the most important sensory system, and the hands are ceaselessly active, exploring clothing, bedding, walls, floors and crevices of the environment. Smoking and drinking of phantom cigarettes and beverages are very common.

As delirium subsides, food and drink previously ignored or refused may be accepted in small amounts, although appetite and thirst are generally decreased. The subject begins to respond to short instructions and may be quite tractable, but at times is negativistic and refuses to cooperate. If he feels annoyed, he may strike out at the source of his annoyance. Attention span is very short and distractability is correspondingly heightened. Drawings and handwritings show marked deterioration.

While incapable of sustained intellectual effort, the subject may persist in an activity in spite of failure, ceaselessly prying at cracks in the wall, for example, in an endeavor to escape from an enclosed area. Sometimes he may succeed in conveying some wish, such as a desire to use the latrine, and then be too confused to execute his intention. At other times, he may react violently to hallucinated events and engage in pantomime combat with phantom assailants or in ludicrous play with imaginary companions.

As recovery proceeds, the subject gradually begins to converse in a more rational and coherent fashion, but his grasp of the situation is still impaired and he often makes paranoid misinterpretations. He may feel, for example, that someone is out to kill him or that his food is poisoned. He may wonder why he is under such scrutiny and why he is being 'treated like a kid'.

While recovering, the BZ-intoxicated subject tends to deny that he is impaired and tries to make excuses for errors or failures during testing or questioning. The casual examiner may be fooled into thinking that little or no impairment is present. During this period, the overall demeanor and manner of acting is sometimes reminiscent of paranoid schizophrenia.

If the reaction lasts more than a day, a period of deep sleep generally precedes full recovery. Return of appetite, interest in recreation and a normal display of enthusiasm and spontaneity in conversation are reliable indications that delirium is over...

[...]

One intriguing finding is the frequent report by subjects, both during and after recovery from the drug experience, of the illusion of red coloration of the skin, both their own and that of undrugged personnel who are with them. One or two individuals have thought their hands were bleeding when washing them under the tap. Whether this is an optical phenomenon related in some way to engorgement of retinal blood vessels or is central in origin is not known.

[...]

With small doses of BZ, excitation is sometimes not seen at all, or is very mild and transient. Instead, sedation is the predominant effect. It is not uncommon for subjects receiving doses between 2.0 and 5.0 mcg/kg at 10:00 hours experimental time (expressed in hrs:min rather than '1000') to sleep through the afternoon, most of the evening, and then through the night, recovering normal alertness by the following morning. This is not attributable simply to boredom, since at very low doses and with other types of agents, daytime sleeping is either absent or limited to short naps.

[...]

Frequently, time 'stands still' for the incapacitated subject, from sometime on the first day until nearly complete recovery, two or three days later. When he 'comes to', he may think it is still the day on which he received the drug, sometimes in the face of external evidence to the contrary. For example, one man commented on the third day of the test: 'You know, if I didn't know it was Friday, Id swear it was Sunday' (which it was). When I asked him to explain, he commented that the Post was nearly deserted, 'like it would be on Sunday.'

[...]

"One subject tried to provoke a fight with a simulated gun mount; another said 'Excuse me, Sir' to the water fountain when he accidentally brushed against it."

With regards to persons in his vicinity, recognition may be accurate for individuals who he has met prior to testing, such as the doctor or nurse; other people may erroneously be greeted as old friends from his outfit, or even relatives. At times he may react to large objects possessing a vertical shape as if they were people. One subject tried to provoke a fight with a simulated gun mount; another said 'Excuse me, Sir' to the water fountain when he accidentally brushed against it. In more extreme states of confusion, he may even initiate conversations with hallucinated individuals. He conducts these one-sided conversations in such a natural, unstudied manner that acting is out of the question.

[...]

Occasionally, he will take vigorous action to deal with imagined emergencies. Subjects may call frantically for medical assistance to treat an illusionary woman who has supposedly just been run over by a car, or shout up at an air-conditioning vent for someone to 'throw down a shotgun and some shells' so he can protect himself from the mob he imagines coming toward his room. One subject scrambled halfway over a seven-foot-high partition, fleeing from a 'guy with a gun' and the nurse caught him by the heels just before he vanished head first down the other side.

[...]

Organized, complex panoramic hallucinations are most common between 24-48 hours after exposure to doses at or above the incapacitating dose. These may be benign or even entertaining – one subject descrbed with great enthusiasm a Lilliputian baseball game being played on the floor in front of him. Later, particularly during the night, the visions may be gigantic and terrifying.

Still later, in place of elephants and giant snakes, he sees rats, squirrels or spiders and gradually these diminish to become bugs or ants, which he labors to brush from his clothing and bedding. Finally, they disappear or a re correctly perceived as pieces of lint, dust, loose threads, raised markings on the door, nail heads, paint drippings or whatever would have been clearly recognized as inanimate a few hours before.

[...]

Another curious disturbance of memory function is perseveration – the tendency to repeat the same response inappropriately. This may take a unique form: the subject initially cannot answer a question and seems unable even to remember what the question was, but when the examiner asks a new question, he replies by correctly answering the first! Simultaneously, he seems not to have heard the second question, nor to realize he has responded inappropriately..."

[...]

After recovery, amnesia is greatest for the period of greatest incapacitation, with fair recall of the onset stage. Amnesia for early phases of recovery is not total at the time of emergence from delirium, but for a while develops further. As time goes by, they fade quickly, in much the same way as dreams recollected in the morning a re forgotten by noon. Many subjects demonstrated that if questioned early, they could recall many of the paranoid misperceptions of the previous day, and in retrospect recognize them as distortions. Later, they did not remember this.

In general, however, very little is permanently remembered for more than a few hours after recovery, which no doubt accounts for the commonly held medical belief that delirium is characterized by subsequent amnesia.

[...]

Speech is slurred, the voice develops a monotonous nasal sound, and its volume wanes to an almost inaudible level. This period of incoherent mumbling is sometimes referred to in older medical literature as 'mussitant delirium' (mumbling delirium).

Handwriting is impaired in quality and is usually reduced in size, sometimes to the point of micrographia. When asked to write on a blackboard, a subject's ordinary natural tendency to compensate automatically for the examiner's increased viewing distance by increasing the size of the letters, does not occur. Once again, the loss of ability to maintain a sense of 'context' seems to be a major problem.

[...]

[The] particular concatenations and distortions of language elements are almost impossible to imitate – they seem to result from an extreme loosening of the entire verbal associative system. As such, they may create a humorous effect,since the shift is so rapid and unpredictable that at times their remarks have the flavor of creativity and wit (the things that subjects say and do, in fact, are often very funny and it is sometimes difficult to keep from laughing at their antics, professional standards of decorum notwithstanding).

During severe delirium, attempts to clarify the intended communication by asking the subject to repeat or explain something are usually futile. It does not good to say 'What do you mean by that?' because the subject does not know what he said, does not really grasp the question and my not realize what he is saying when he answers.

[...]

Unlike schizophrenic psychosis, familiar to the clinician, delirium at its height shows no thematic consistency, no trend and no obsessional preoccupation with a single related set of delusional ideas, systematically connected in a persecutory or grandiose system. Instead there is a marked loosening of associations approaching randomness, muttered phrases, outbursts of profanity, scattered references and allusions to other times and places, brief periods of intense examination of trivial objects, facial expressions of perplexity or wonderment, chuckling amusement or tender concern, repetitious fingering of bedclothes or pajamas, sudden requests for information or personal articles (which are promptly forgotten) and so forth ad infinitum. When addressed the response is often courteous and noncommittal, such as 'Fine, Sir' in answer to the inquiry "How do you feel?.

[...]

Such individuals seem unable to appreciate the reality of their deficits, and will offer ridiculous alibis and wildly implausible explanations for their failure to perform adequately in the areas affected by their intoxication. Stalling and temporizing maneuvers are common, such as asking the examiner to repeat the question, or asking for clarification of the instruction when in fact they have completely forgotten it, inquiring naively 'You mean me?' or 'Did you want me to do that right now?'.

[...]

Paradoxically, one of the most reliable indications of recovery is the return of awareness by the subject that he is not as proficient as he should be. Subjects who received an incapacitating dose usually regain this awareness by the third or fourth day. By this time, their objective performance on addition and word recognition tests has generally risen to 80 or 90 percent of their baseline level, and the principal symptoms are some residual lassitude and blurring of vision..."